Hello, so I am used to the PBR Metal Rough from substance formats.
When plugging in my nodes, the specular is not grayed out, and I cant find a way to make it as such,
So is just leaving it unplugged the same as it being grayed out?
With the nodes that are not grayed out but you dont have the need for them, or there values are unknown to you, what is the solution?
Thanks.
yea, just dont add a value to it
It’s mostly there for legacy reasons, special case materials, or non PBR stuff.
Specular can be handy, but dont use it as a replacement for roughness.
For most cases, not touching spec. is fine, but for things like crystals, diamonds, and other noble-esque metals can benefit from it.
Occasionally I also use it to affect the reflective color a little bit.
sure there are rules when it comes to pbr, but as an artist we are allowed to bend them to get the result we want 
Awesome thanks, yea I am not replacing rough for spec, but I have been spending time playing with its value, to see if it looks more accurate.
As I know its heavily based on your lighting and environment setup, but I have a hard time getting my materials to look like they do in substance. I seem to get the best result when I use t he pbr metal rough export preset than I do with the UE4 packed preset.
The only thing that really comes out all to lunch thats WAY!!! off from substance viewports are the opacity channels.
So I have been just making all my opacity stuff its own material and not painting them at all, just using unreals vector nodes to control my look, which is working out fine, as long as I dont want to included grunge or scratched details.
It seems like quality opacity in unreal is very advanced user, and sucks substance cannot export out opacity in a plug and play manner, even when I used designer and made a SBSAR, the opacity was super wrong.
Make sure your roughness has sRGB unchecked in UE4.